Field of the Invention
The invention relates to a semiconductor structure and particularly relates to a power transistor device.
Description of Related Art
The power switch transistor has already been widely used in the field of power management, in which an ideal power switch should have the characteristics of low on-resistance and high breakdown voltage, so as to ensure the power conversion efficiency of the power management circuit and to provide an excellent current-handling capacity. In addition, the conventional transistor device remains unidirectionally conductive when the transistor is in a turn-off state because the conventional transistor device has a body diode. In order to enable a switch device to be in a bidirectionally turn-off state, a pair of transistors connected in series is usually required to achieve said effects. However, such a structure enhances the on-resistance of the transistor device and complicates the control thereof. In light of the above, people having ordinary skill in the art have been researching on how to reduce the on-resistance of the transistor device and enhance the bidirectional breakdown voltage thereof.